I tried the AmigaWriter 2.2 demo and it made my 4000/040/40 crawl. It was like running geoWrite on a half-speed C64. I'm sure it runs better on an 060/50, but I have not tried.
Like someone else here, I use(d) WordPerfect 4.2. While still in college a number of years back I made the switch from geoWrite 128 on GEOS 128 v2 to WordPerfect 4.2 on Amiga. It did well for me up until professors began requiring Office XP/2003 documents (not to mention the need for spreadsheets in chem and bio,) to which I responded with a mix of StarOffice and Microsoft Office.